Overload and reverse current relay device.



E2 CONRAD. v OVERLOM) AND REVERSE QURBENT RELAY-9mm.

mme@ Sept. mi, 999.

APPLXUAHO FILED 15531.15, 1909.

WHMSSES; mvmmw JMzff/L j? v BY mi Y e vri ji NNW@ naar binnenin@ uni ern' unies.

FRANK CONPUD, QF

Q'VERLGAD AND REVERSE CURRENT RELAY DEVICE.

Spccieetion of Lettersfatent. Petten-ted lie/pt. 14,

Original application filed May 8. 19G5, Serial Ncf. Divided and 'this application filed March 15,

To all whom it may concern:

Be it known that l, FRANK Corman, a c1tizen of the United States, and a resident of.

Swissvale, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in @verload and Reverse Current Relay Devices, of which the following' is a speelde-ation, this 'being a division of my application Serial No. 259,388, tiled lilay, 1905.

My invention relates to protective means for electric circuits, and particularly to relay devices that control the operation of circuit-protective apparatus.

The object of my invention is to provide a relay device which shall insure operation of the circuit-protective .apparatus when the directionof the drop ot' potentialir. the circuit becomes reversed, or when the current traversing the circuit exceeds a predetermined amount, regardless of the voltage or power factor of the circuit.

Relay' devices ci the general character' indicated above have usually embodied means for producing' a `force cr torque approxi.- inately proportional to the product of the current, volt-age and power factor or" the circuit it was intended to protect. Such devices have operated imperfectly, because when an undue amountof current traverses a circuit, the voltage and power factor of the circuit may drop considerably and consequently suiiicient torque may not be eX- erted to operate the instrument and trip the circuit-breakers when it is most necessary that the circuit-breakers be opened. Means have sometimes been embodied in'v such de vices for increasing the torque in propor tion to decrease in voltage, but the devices have usually been very complex in structure, and, so far as I am aware, no relay device has heretofore been constructed that was operative regardless of changes both in voltage and in power factor.

Besides the usual wattmeter device for producing` a torque, my invention embodies a torque-producing means that is .responsive to the amount of current traversing the circuit, the two' torques being normally opposed. lf the current traversing the circuit Serial No. 483,659.

I exceeds a predetermined amount, the torque l that is dependent upon the current alone may exceed that which is dependent upon the product of current, voltage and power factor (which, as before explained, may be small on account ot the" decrease in voltage and power vfactor) by such an amount aste effect operation of the device and cause the circuit-breaker to open. It, for any reason, the current reverses its di- Y rection; that is, if the direction of the drop of potential inthe circuit becomes reversed, the two torques act in the same direction, and if the total torque-exceeds a predetermined amount, the device will operate and cause the circuit-breaker to open. v

igure 1 of the accompanying drawing illustrates, diagrammatically, a system embodying my invention, and Fig. 2 is a diagram of torque curves pertaining to my 'invention. A. polyphase supply circuit, comprising conductors 1, 2, 3 and 4, is protected by meansof a circuit breaker 5 that is provided with a tripping coil 8, the circuit of which is opened and closed by means of a switch arm 7 that is normally maintained in open circuit position by means of'a -spring 8, and is adapted to be moved into engagement with the-contact terminal 9 by means ot a movable member, such as a shaft 11 of the protective relay constituting the present invention. The relay comprises, further, two devices 12 and 13 each ot which is adapted to operate both as a Wattmetcr and as an an'nneter, the Watt-meter and ammeter torques being' normadly opposed. Themovable elements of the devices 12 and 13 are cylinders 1e and 15 of conducting material that are mounted upon the shaft 11 and rigidly connected thereby. Each of cylinders 14 and 15 is embraced by opposing concave polar projection 1G of a U-shaped magneti-zahle core 17, that is provided with a main 'winding 18 upon its body portion and with air auxiliary Winding 19 that is located in slots in the polar projection 116 and surrounds the ends of the U-shaped core. The windings are supplied with current from transformers '20 that are connected, respectively, between `conduct-ors belongingto different phases ot the supply circuit, and the windings lt) are supplied with current from transtori'ners 2l the primary windings ot which are cfmnected in series with conductors belonging, respectively7 to dill'crent, phases ot the supply circuit. lt

will he noted that the connections and ai'-,

rangements of thc circuits are such thaty dcvices 12 and l?) are associated with ditl'erent phases ot the supply circuit.y so that the relay will respond, by reason o'l" the. rigid connection between the movable members l-lV and l5 ol t'lnI dcviccsiuto abnormal conditions existing in either ott the phases of the circuit. 'lhe recess in the polar projections of the magnetizable core ott each device divides the said polar projections into two parts and each part is recessed for the reception of clos-Jed circuit windings or coils 22 that ett'ect displacement of the phase of the portions of the tluxes that traverse the spaces between the polar projections. The said coils cooperate with the winding lt) to cause a torquel to he exerted upon the mov; ble member ot the device that is dependent only upon the amount ot' currentv traversing the Supply circuit.y and the windings -ttl and 19 cooperate to cause a torque to be upon the movable member ot' the device that is dependent upon the amount ot energy traversing the supply l circuit. and these torques normally oppose each other. ln order to retard the movement:-` ot the sha t't ll and the switch arm 7, theI shalt. may he provided with any suitable retarding devicV77 such as t'an blades 2?).

The operation ot' the system may beunderstood t'rom a consideration of the curves ot Fig. 2, in .which tl e abscisszry are proportional to the, amount, oll current traversing a circuit'. and the ordinates are proportional to the torquesv exerted upon the conducting disks. curve represents the variations in the torque due to variations in the amount ol' current, and, it has apru'oximately the t'orm ot' a parabola7 since the, torque varies approximately in proportion to the square otl the current. Curve \\v is that ot the wattmcter device, and. t'or ltlt) per cent. power t'actor7 it is approximately a straight lineI7 since the torque oll the wattmetcr device is approximately prtmortional to the first power ot the current, The two curves cross ata point u, under which conditions the two torques are exactly balanced. y/

Now let, ity be assumed that to move the switch-arm@ against the torce exerted by the Spring S, a torque is required which is equal to that rtqnesented by the length 'of the ordinate O-itw. 'lhen when the, current traversing the circuit either equals or, yezicecds that reprcsenttul by the lenfth of the abscissae 0---39, the torque exerted )y the ammeter device will exceed that exerted by the wattmeter device by an amount either equal eersel to 0r in exdess ot that repr L I the length of the ordinate 0-38, and the switcharm 't' will then be moved into eiigagement with the contact terminal t), thereby completing the circuit of the operating magneti winding t3 and causing the circuit-hrealnu 5 to open. lf a curr-ent equal to that represented by the length of the abscissa 0-40 traverses the circuit in. a direction opposite to the normal direction, 'the torque exerted by the ammeter device will be represented hy the length of ordinate 0-4l and the torque exerted by the wattmeter device will be rep-l resented by the length of the ordinate G-fl-Q. These two torques will act .in the same direction so that the total torque will be represented hy the sum of the ordinates O-Ltl and (1l-t2 and will be equal to the torque represented by the ordinate 0-38. lf the sum of 'the torques is equal to or exceeds the length ot' ordinate O-BS, the switch-arm 7 will he moved into engagement with the contact ter-| minal t), the operating magnet Winding t3 will be energized and the circuit-breaker 5 will be caused to open. t will he noted that the switch-arm i moves into ei'igagen'ient with the contact'y terminal 9 whether operated on account ot an excessive current in the supply circuit or on account o'lE a reversal ot the direction of the drop of pfjitential` be cause the direction of the torque of the wattmeter mechanism changes when the direct'ion of the drop of potential in the circuit reverses.

l. claim as my invention:

l. The combination with a movable conducting member, a magnetizahle core comprising a y'oke and pole pieces having reduced portions and projections adjacent to the movable member, ot a winding located on the yoke ot' the core7 a winding surrounding the reduced portions ot the pole pieces`r and closed circuit, windings surroui'uling certain ot' the pole piece projections.-

L). 'the combination with a supply circuit'` a movable conducting member, and a magnetizable core comprisinga yoke and recessed pole pieces adjacent, to the conducting n'iember, of a magnetizing winding located on the yoke ot the core upon which a voltage may be impresstwl that is proportional to the voltage of the circuit, a winding located in certain of the pole piece recesses that. may be supplied with an amount of`current which is proportional to the amount traversing the supply circuit, and closed circuit'. conductors surrounding portions of the pole piece projections.

il. The combination with a supply circuih a'movable conducting member, and ay magnetizable core c(' m] irising` a yoke and rccessed pole pieces, of a magnetizing wind-- .ing located on the yoke of the core on which a voltage may be impressed thatl is proportra tional to thevoltage of the circuit, a magnetizing Winding surrounding the core and In testimony whereof,V have hereuntfo subscribed my name this 10th day of March;

located in ertaln of the polev piece recesses 1909.

that may be supplied With an amount traversmg the circuit, and c1osed circuit conductors that surround portions of the pole piece' projections.. 4

. FRANK CONRAD. Witnesses `WM. BRADSHAW, 'B B. HINES. 

